Grand Canyon, Ariz. ? After 10 hours and 22 miles, the finish of our Grand Canyon rim-to-rim hike was in sight.

Unfortunately, to see the finish, I had to look up. Way up.

Nearly two more miles of steep switchbacks had to be climbed on feet that were not used to going up more than two flights of stairs at a time, and in broiling afternoon sun that was zapping every last ounce of energy.

Many hikers, tourists and mules were along the popular Bright Angel Trail on this Thursday in June, but I was among only five people who were attempting to hike from the North Rim to the South Rim in one day.

My friends Edwin Hovsepian and Kay Ogden, whom I met on a world bicycle trip in 2000, were several switchbacks higher. The other rim-to-rim hikers, a father and son from Columbia, Md., were several switchbacks lower.

Hovsepian, an accountant from Glendale, Calif., read about the hike in an in-flight magazine and solicited people to join him via a mass email: “It sounds like a cool thing to do actually, it will probably be very hot. They recommend that you do it in 2-3 days, or risk illness, dehydration or death!

“They did say, however, that it is not Guinness Book material and that dozens of people do it every year.”

Maureen Oltrogge, the Grand Canyon National Park Services public affairs officer for the past 17 years, said Tuesday: “It’s certainly not illegal, but please put in a strong caution. It’s not something recommended by the National Park Services, especially in the summer months when the temperatures rise over 110 degrees.

“Even for people who think they are physically fit and can meet the challenge, we have seen fatalities on the trail. People go into shock through heat exhaustion and over-saturating their bodies with water.”

Before going on the hike, I read several guidebooks on Grand Canyon, and they all echoed Oltrogge’s sentiment. One book said to read “Over the Edge: Death in Grand Canyon.” The subtitle: “Gripping accounts of all known fatal mishaps in the most famous of the World’s Seven Natural Wonders.”

When I called Hovsepian to tell him that nearly 600 people have died in Grand Canyon, he said: “Clark, you’re not wimping out, are you?”

I decided not to read the book with a picture of the skeletal remains of one hiker on the cover until after the hike. But I did go buy every safety item recommended, including a whistle, mirror, matches, first-aid kit and salt tablets.

Ogden, a Houston resident who completed the grueling Paris-Brest-Paris endurance 650-mile bike ride last year, would supply the electrolytes.

We also started the hike armed with the information that over the years some people have run rim-to-rim-to-rim in one day. The elevation change for the 50 miles is almost the same as from base camp to Mt. Everest’s summit.

Hiking was enough for Hovsepian, Ogden and I. We hitchhiked two miles to the North Kaibab Trailhead to get a 5 a.m. start, just as the sun was coming up. Temperatures were in the high 40s.

In most hikes, the start is at the bottom. But this one began at the top at an elevation of 8,250 feet. Indians and prospectors originally used the route that winds more than a vertical mile down into the canyon, along zigzagging red-dirt paths that hugged limestone and shale rocks.

We would pass through four climatic zones during our 14-mile route to Phantom Ranch, a complex of cabins and camp sites built in 1922.

With much of the hike in cool temperatures and in shade, we made it to the canyon oasis at 11 a.m. The father and son were already there, enjoying lunch at a picnic table in the shade. None of us was tired, although Ogden’s knee and my big toe were aching.

I knew the worse was yet to come.

We had a slightly heated discussion over which trail we would take up: the 7.3-mile South Kaibab or the 9.3-mile Bright Angel. The South Kaibab was shorter, but steeper and followed the open ridgeline that is great for panoramic views but provides no shade.

I wanted us to take the Bright Angel, which meandered along the river before going the one vertical mile up to the South Rim. There also were water sources and shady spots for respite from the sun.

The decision was made when I said I would buy the drinks if we took Bright Angel.

We left at noon, another thing the guidebooks say not to do. But we were fortunate that temperatures were about 15 degrees cooler than normal, although still around 100 degrees.

Ogden and Hovsepian reached the top at 5 p.m., exactly 12 hours after they started. I made it 20 minutes later. The father and son finished shortly afterward.

I was exhausted. Ogden’s knee was badly swollen. And Hovsepian was admiring his worn sneakers.

The hike definitely can be better appreciated over the recommended 2-3 days. But to do it in one day is a feat.